Kloeckera taiwanica sp. nov., an ascomycetous apiculate yeast species isolated from mushroom fruiting bodies.

Three apiculate yeast strains, EJ7M09(T), GJ5M15 and GJ15M04, isolated from mushrooms in Taiwan were found to represent a novel species of the genus Kloeckera. The phylogenetically closest relative of this novel species is Hanseniaspora occidentalis, but the type strain of H. occidentalis differed by 4.6 % divergence (25 substitutions; 5 gaps) in the sequence of the D1/D2 domain of the large subunit rRNA gene. This difference clearly suggests that the three strains represent a distinct species. As none of the strains that were examined in this study produced ascospores or exhibited conjugation on common sporulation medium either alone or in a pairwise mixture, this species could be considered as an anamorphic member of the genus Hanseniaspora, and a novel species, Kloeckera taiwanica sp. nov., is proposed, with EJ7M09(T) ( = BCRC 23182(T) = CBS 11434(T)) as the type strain.

Three new species of bipolar budding yeasts of the genus Hanseniaspora and its anamorph Kloeckera isolated in Thailand.

In the course of a survey of yeast biodiversity in the natural substrates in Thailand, eight strains were found to represent three hitherto undescribed species of Hanseniaspora/Kloeckera. They were isolated from insect frass, flower, lichen, rotted fruit and rotted wood. Based on the morphological and physiological characteristics, and sequences of D1/D2 domain, six strains represent a single species of the genus Hanseniaspora, described as Hanseniaspora thailandica sp. nov. (type BCC 14938(T)=NBRC 104216(T)=CBS 10841(T)), and another strain as Hanseniaspora singularis sp. nov. (type BCC 15001(T)=NBRC 104214(T)=CBS 10840(T)). A further strain, which belongs to Kloeckera and does not produce ascospores, is described as Kloeckera hatyaiensis sp. nov. (type BCC 14939(T)=NBRC 104215(T)=CBS 10842(T)). Strains belonging to H. thailandica sp. nov. differed by 17-19 nucleotide substitutions from Hanseniaspora meyeri, the closest species. DNA reassociation between the two taxa showed 30-48% relatedness. Kloeckera hatyaiensis sp. nov. and H. singularis sp. nov. differed by eight and 16 nucleotide substitutions with one gap from the nearest species, Hanseniaspora clermontiae and Hanseniaspora valbyensis, respectively.

Influence of wine-related physicochemical factors on the growth and metabolism of non-Saccharomyces and Saccharomyces yeasts in mixed culture.

The influence of two physicochemical factors involved in winemaking, temperature and SO(2), on the kinetics and metabolic behavior of Kloeckera apiculata and Saccharomyces cerevisiae was examined. Highest biomass was reached at 15 and 25 degrees C for K. apiculata and S. cerevisiae, respectively. Pure cultures of K. apiculata died off early with increasing temperature, but in co-culture with S. cerevisiae it showed higher viability and a change in the death curve from exponential to linear. Statistical analysis revealed that metabolite production was significantly different for the three cultures and also at the different fermentation temperatures. Besides, the interaction between culture type and temperature was significant. At temperatures from 15 to 30 degrees C the mixed culture showed similar ethanol and lower acetic acid production compared with a pure culture of K. apiculata. SO(2) addition slightly increased survival of the non-Saccharomyces species in pure and mixed cultures. Statistical evaluation indicated that culture type and SO(2) addition significantly affected metabolite production, but the interaction between culture and SO(2) was not significant. These results contribute to current knowledge of enological factors and their effect on prevalence and fermentative activities of the composite yeast flora and the statistical significance emphasizes the importance of the combined influence of the culture type and physicochemical factors on the production of fermentation metabolites.